timekeeper
noun [ C ] uk/ˈtaɪmˌkiː.pər/ us/ˈtaɪmˌkiː.pɚ/
计时员;计时器
an object or person that records (an amount of) time
There's no point in having a clock which looks attractive if it isn't a good timekeeper (= if it doesn't show the correct time). 一个好看但走时不准的钟没有什么用。
（比赛或工作的）计时员
a person who records the amount of time that people taking part in a race or competition take to finish the race or competition, or the amount of time that people at work spend working on their jobs
a good/bad timekeeper （尤指在工作上）通常守时／迟到的人
a person who usually arrives on time/late for something, especially work